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Re: NCRS will have to learn this is not 1957
My machine shop also 'cooks' block/head castings. In addition to buring out grease/oil/soot, there are other side benefits.
(1) Iron and iron oxide (rust) have different thermal expansion coefficients. The process 'spalls' rust from the walls of the water jacket passages that gets blown out with compressed air leaving a nearly 'as cast' fresh surface for good heat transfer.
(2) His technique elevates temperature in a klin to about 25-30 degrees below the melting point of cast iron. He's convinced that this heat soak relieves the parts of strain induced by years of being bolted together with interleaved gaskets during the stress of repeated engine thermal cycling (start up/shut down). He feels the heat soak will either cure existing stress points that could crack open or make 'em fail then & there.
There could be merit to this as even though the parts are below their melting point, individual molecules will randomly exceed the melting point allowing the metal to flow on a micro basis.... He heats the parts and lets them soak overnight. Heat is removed and it takes a full day for the kiln temperature to drop to ambient.
My machine shop also 'cooks' block/head castings. In addition to buring out grease/oil/soot, there are other side benefits.
(1) Iron and iron oxide (rust) have different thermal expansion coefficients. The process 'spalls' rust from the walls of the water jacket passages that gets blown out with compressed air leaving a nearly 'as cast' fresh surface for good heat transfer.
(2) His technique elevates temperature in a klin to about 25-30 degrees below the melting point of cast iron. He's convinced that this heat soak relieves the parts of strain induced by years of being bolted together with interleaved gaskets during the stress of repeated engine thermal cycling (start up/shut down). He feels the heat soak will either cure existing stress points that could crack open or make 'em fail then & there.
There could be merit to this as even though the parts are below their melting point, individual molecules will randomly exceed the melting point allowing the metal to flow on a micro basis.... He heats the parts and lets them soak overnight. Heat is removed and it takes a full day for the kiln temperature to drop to ambient.
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